video: add VideoController, which hold cached metadata and mute states

Closes: https://github.com/damus-io/damus/pull/1539
Reviewed-by: William Casarin <jb55@jb55.com>
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Views/Video/VideoController.swift

@@ -0,0 +1,40 @@
+//
+//  VideoController.swift
+//  damus
+//
+//  Created by Bryan Montz on 9/3/23.
+//
+
+import Combine
+import Foundation
+
+struct VideoMetadata {
+    let has_audio: Bool
+    let size: CGSize
+}
+
+final class VideoController: ObservableObject {
+    private var mute_states: [URL: Bool] = [:]
+    private var metadatas: [URL: VideoMetadata] = [:]
+    
+    @Published var focused_model_id: UUID?
+    
+    func toggle_should_mute_video(url: URL) {
+        let state = mute_states[url] ?? true
+        mute_states[url] = !state
+        
+        objectWillChange.send()
+    }
+    
+    func should_mute_video(url: URL) -> Bool {
+        mute_states[url] ?? true
+    }
+    
+    func set_metadata(_ metadata: VideoMetadata, url: URL) {
+        metadatas[url] = metadata
+    }
+    
+    func metadata(for url: URL) -> VideoMetadata? {
+        metadatas[url]
+    }
+}